• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.486-492
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• 2015

Radiation source imaging system is essential for protecting of radiation leakage accidents and minimizing damages from the radioactive materials, and is expected to play an important role in the nuclear plant decommissioning area. In this study, the stereoscopic camera principle was applied to develop a new radiation imaging device technology that can extract the radiation three-dimensional position information. This radiation three-dimensional imaging device (K3-RIS) was designed as a compact structure consisting of a radiation sensor, a CCD camera, and a pan-tilt only. It features the acquisition of stereoscopic radiation images by position change control, high-resolution detection by continuous scan mode control, and stereoscopic image signal processing. The performance analysis test of K3-RIS was conducted for a gamma-ray source(Cs-137) in radiation calibration facility. The test result showed that a performance error with less than 3% regardless of distances of the objects.

• Journal of Radiation Protection and Research
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• v.49 no.2
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• pp.68-77
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• 2024

Background: Cone beam computed tomography (CBCT) is essential for correcting and verifying patient position before radiation therapy. However, it poses additional radiation exposure during CBCT scans. Therefore, this study aimed to evaluate radiological safety for the human body through dose assessment for CBCT. Materials and Methods: For CBCT dose assessment, the depth dose was evaluated using a cheese phantom, and the dose in the orbital area was evaluated using a human body phantom self-fabricated with a three-dimensional printer. Results and Discussion: The evaluation of radiation doses revealed maximum doses of 14.14 mGy and minimum doses of 6.12 mGy for pelvic imaging conditions. For chest imaging conditions, the maximum doses were 4.82 mGy, and the minimum doses were 2.35 mGy. Head imaging conditions showed maximum doses of 1.46 mGy and minimum doses of 0.39 mGy. The eyeball doses using a human body phantom model averaged at 2.11 mGy on the left and 2.19 mGy on the right. The depth dose ranged between 0.39 mGy and 14.14 mGy, depending on the change in depth for each imaging mode, and the average dose in the orbit area using a human body phantom was 2.15 mGy. Conclusion: Based on the experimental results, CBCT did not significantly affect the radiation dose. However, it is important to maintain a minimal radiation dose to optimize radiation protection following the as low as reasonable achievable principle.

• Imaging Science in Dentistry
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• v.54 no.1
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• pp.1-11
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• 2024

Purpose: This study was conducted to investigate the safety of dental imaging in pregnant women with respect to fetal health. Materials and Methods: Searches were conducted of the PubMed, Scopus, and Web of Science databases in May 2023. The inclusion criteria encompassed cross-sectional and longitudinal studies that focused on the analysis of diagnostic dental imaging in pregnant women, as well as studies utilizing phantoms to simulate imaging examinations. The exclusion criteria consisted of reviews, letters to the editor, book chapters, and abstracts from scientific conferences and seminars. Results: A total of 3,913 articles were identified. Based on a review of the titles and abstracts, 3,892 articles were excluded, leaving 21 articles remaining for full-text review. Of these, 18 were excluded, and 4 additional articles were included as cross-references. Ultimately, 7 articles underwent quantitative-qualitative analysis. Three retrospective studies were focused on pregnant women who underwent dental imaging procedures. The remaining 4 studies utilized female phantoms to simulate imaging examinations and represent the radiation doses absorbed by the uterus or thyroid. Conclusion: Few dental radiology studies have been conducted to determine the safe radiation threshold for pregnant women. Additionally, the reviewed articles did not provide numbers of dental examinations, by type, corresponding to this dose. Dental imaging examinations of pregnant women should not be restricted if clinically indicated. Ultimately, practitioners must be able to justify the examination and should adhere to the "as low as diagnostically acceptable, being indication-oriented and patient-specific" (ALADAIP) principle of radioprotection.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.32-34
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• 2002

Over the past two decades there has been a tremendous growth in the number of synchrotron radiation facilities in the world and also in Japan. The high flux and brightness radiation which derive from the third generation low emittance rings provide an ideal source for many applications in the medical sciences. The application of synchrotron radiation to medical imaging started in the early 80's in U.S.A, followed by European countries such as Germany and Russia. In Japan, researchs on intravenous coronary angiography started in 1884 at the Institute for High Energy Phisics(KEK) in Tsukuba. At present, it is the only application of syncrotron radiation which is at the stage of human study. In '90s, newer techniques such as phase and refraction contrast imaging appeared which are at the in vitro or animal study stage. Various types of x-ray CT have also been developed for three-dimensional imaging of the subjects. The present status of medical applications of synchrotron radiation in Japan is reviewed.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.371-376
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• 2014

The process of flip-chip bump bonding, Au wire bonding and encapsulation were sucessfully developed and modularized. The CdTe sensor and ROIC were optimally jointed together at $150^{\circ}C$ and $270^{\circ}C$ respectively under24.5 N for 30s. To make SnAg bump on ROIC easy to be bonded, the higher bonding temperature was established than CdTe sensor's. In addition, the bonding pressure was lowered minimally because CdTe Sensor is easier to break than Si Sensor. CdTe multi-energy sensor module observed were no electrical failures in the joints using developed flip chip bump bonding and Au wire bonding process. As a result of measurement, shearing force was $2.45kgf/mm^2$ and, it is enough bonding force against threshold force, $2kgf/mm^2s$.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.475-481
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• 2014

The aim of this work was to develop the gamma camera system for small animal gamma imaging and environmental radiation monitoring imaging using a parallel hole collimator and pinhole collimator. The small gamma camera system consists of a CsI(Tl) scintillation crystal with 6 mm in thickness and $50{\times}50mm$ in area coupled with a Hamamatsu H8500C PSPMT, are resistive charge divider, pre-amplifiers, charge amplifiers, nuclear instrument modules (NIMs), an analog to digital converter and a computer for control and display. We have developed a radiation monitoring system composed of a combined pinhole gamma camera and a charge-coupled devices (CCD) camera. The results demonstrated that the parallel hole collimator and pinhole collimator gamma camera designed in this study could be utilized to perform small animal imaging and environmental radiation monitoring system. Consequently in this paper, we proved that our gamma detector system is reliable for a gamma camera which can be used as small animal imaging and environmental radiation monitoring system.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2783-2787
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• 2013

To assess the risk of cancer incidence after medical radiation exposure for coronary artery disease (CAD), a retrospective cohort study was conducted based on Taiwan's National Health Insurance Research Database (NHIRD). Patients with CAD were identified according to the International Classification of Diseases code, 9th Revision, Clinical Modification (ICD-9-CM), and their records of medical radiation procedures were collected from 1997 to 2010. A total of 18,697 subjects with radiation exposure from cardiac imaging or therapeutic procedures for CAD were enrolled, and 19,109 subjects receiving cardiac diagnostic procedures without radiation were adopted as the control group. The distributions of age and gender were similar between the two populations. Cancer risks were evaluated by age-adjusted incidence rate ratio (aIRR) and association with cumulative exposure were further evaluated with relative risks by Poisson regression analysis. A total of 954 and 885 subjects with various types of cancers in both cohorts after following up for over 10 years were found, with incidences of 409.8 and 388.0 per 100,000 person-years, respectively. The risk of breast cancer (aIRR=1.85, 95% confidence interval: 1.14-3.00) was significantly elevated in the exposed female subjects, but no significant cancer risk was found in the exposed males. In addition, cancer risks of the breast and lung were increased with the exposure level. The study suggests that radiation exposure from cardiac imaging or therapeutic procedures for CAD may be associated with the increased risk of breast and lung cancers in CAD patients.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1671-1680
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• 2014

There are always much concern about the leakage of radiation materials in the event of dismantle or unexpected accident of nuclear power plant. In order to remove the leakage of radiation materials, appropriate dispersion detection techniques for radiation materials are necessary. However, because direct handling of radiation materials is highly restricted and risky, developing radiation-related techniques needs computer simulation in advance to evaluate the feasibility. In this paper, we propose a radiation imaging technique which can acquire 3D dispersion information of radiation materials and tested by simulation. Using two virtual 1D radiation sensors, we obtain stereo radiation images and acquire the 3D depth to virtual radiation materials using stereo disparity. For point and plane type virtual radiation materials, the possibility of the acquisition of stereo radiation image and 3D information are simulated.

• Radiation Oncology Journal
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• v.27 no.1
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• pp.42-48
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• 2009

Purpose: The introduction of image guided radiation therapy/four-dimensional radiation therapy (IGRT/4DRT) potentially increases the accumulated dose to patients from imaging and verification processes as compared to conventional practice. It is therefore essential to investigate the level of the imaging dose to patients when IGRT/4DRT devices are installed. The imaging dose level was monitored and was compared with the use of pre-IGRT practice. Materials and Methods: A four-dimensional CT (4DCT) unit (GE, Ultra Light Speed 16), a simulator (Varian Acuity) and Varian IX unit with an on-board imager (OBI) and cone beam CT (CBCT) were installed. The surface doses to a RANDO phantom (The Phantom Laboratory, Salem, NY USA) were measured with the newly installed devices and with pre-existing devices including a single slice CT scanner (GE, Light Speed), a simulator (Varian Ximatron) and L-gram linear accelerator (Varian, 2100C Linac). The surface doses were measured using thermo luminescent dosimeters (TLDs) at eight sites-the brain, eye, thyroid, chest, abdomen, ovary, prostate and pelvis. Results: Compared to imaging with the use of single slice non-gated CT, the use of 4DCT imaging increased the dose to the chest and abdomen approximately ten-fold ($1.74{\pm}0.34$ cGy versus $23.23{\pm}3.67$cGy). Imaging doses with the use of the Acuity simulator were smaller than doses with the use of the Ximatron simulator, which were $0.91{\pm}0.89$ cGy versus $6.77{\pm}3.56$ cGy, respectively. The dose with the use of the electronic portal imaging device (EPID; Varian IX unit) was approximately 50% of the dose with the use of the L-gram linear accelerator ($1.83{\pm}0.36$ cGy versus $3.80{\pm}1.67$ cGy). The dose from the OBI for fluoroscopy and low-dose mode CBCT were $0.97{\pm}0.34$ cGy and $2.3{\pm}0.67$ cGy, respectively. Conclusion: The use of 4DCT is the major source of an increase of the radiation (imaging) dose to patients. OBI and CBCT doses were small, but the accumulated dose associated with everyday verification need to be considered.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.1
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• pp.7-11
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• 2011

As applications of radiation grow wider from use in the early detection of lesions and preventive diagnosis purposes to the treatment of diseases, the possibilities for patients and working professionals to be exposed to radiation are becoming greater than ever. This can not only directly bring about an increase in patient's individual radiation exposure, but also brings about an increase in the annual radiation dose of working professionals. Therefore, research and countermeasures to reduce radiation dosage are required. In this study, space dosimetry has been divided into two separate measuments with an understanding of the increasing number of angiography procedures: front perspective and side perspective. According to the results of the isodose curve, a way to minimize radiation exposure in working professionals has been suggested. This was made possible by workers through awareness of suitable working positions.